Bingham, M.G., Willemen, A., Wursten, B.T., Ballings, P. and Hyde, M.A.(2015). Flora of Zambia: List of species with each spot-character: Calyx with an epicalyx.http://www.zambiaflora.com/speciesdata/species-spot-display.php?species_id=902, retrieved 31 March 2015